After A/B'ing from the DX50 and my Sony F-807 headphone amp, and my RSA Shadow and Hornet amps with various IEM's and my HD700's, I would also have to disagree. Its not that the built in headphone amps are bad, just a good quality external amp is better.

Like I wrote before, there are very few reasons why you would need an outboard amp and they are all some form of compensation: either your headphones are too hard for the onboard amp to drive and you need more power to compensate, you're wearing balanced headphones which require balanced output, or you have stack envy and feel a need to compensate for that.

If your headphones hiss because they're too sensitive then you don't need an amp. You need an impedance adapter. If you use an outboard amp anyway then that's just stack envy.

Until 1.2.6 I was happy with DX50 and no amp. With the arrival of 1.2.7 I had an intense dislike of the sound. I looked in the for sale area of this very oracle and purchased a second hand amp. By using the line out to amp route, I now find the sound to be constant no matter which firmware is installed. My advice to anyone is to try it and see - at this time I would not return to unamped.

After A/B'ing from the DX50 and my Sony F-807 headphone amp, and my RSA Shadow and Hornet amps with various IEM's and my HD700's, I would also have to disagree. Its not that the built in headphone amps are bad, just a good quality external amp is better.

You've missed the point.

Music players don't need amplifiers. Headphones need amplifiers. When the question is something like, "does DX50 need an amplifier?" then the answer is always "no". It does not.

When the question is something like, "do my headphones need an amplifier?" then the answer falls under what I've written: either they do for some technical reason or they don't. Everything else is stack envy. This includes wanting -- that is, the desire rather than the requirement -- some perceived improvement in sound quality which may or may not actually exist for a given set of headphones and ears and brain and listening environment, and especially when an inexpensive widget will do just as well.

See the analog outputs on the right? That's all analog domain. The firmware doesn't touch any of that; all signal processing happens in the digital domain. Note carefully that there is one set of analog outputs: left channel positive/negative, right channel positive/negative, and mid rail left/right. These are split with one branch going to the line out and the other going to the headphone op-amp. You can see this for yourself in photographs of the circuit board (ask Google about "ibasso dx50 teardown").

Any firmware change that affects the headphone output will have an identical effect on the line out.

From this I can draw two possible conclusions:

First is that there are no changes from v1.2.6 to v1.2.7. Any changes that you perceive are in your own perceptions. That is, in your own mind rather than anything measurable in the real world.

Second is that there are actual, detectable changes between v1.2.6 and v1.2.7. The lack of change that you perceive between the two is in your own perceptions. That is, you want the line out to be "good" so strongly that it colors your perception of the differences.

So this is my DX running it's music library from a 1tb HD. You just need an power source (either charger or a laptop) and away it goes.

Coolness. You might want to try to find a portable battery pack, the kind used for charging phones and tablets, and see if it will supply enough juice to run the HDD for a respectable period.

You might even take a look at Samsung's new 840 EVO SSDs. There is a 1TB model in a 2.5" form factor. Potentially very portable, and the benefit to flash in this application is that it only draws power when being read.

Music players don't need amplifiers. Headphones need amplifiers. When the question is something like, "does DX50 need an amplifier?" then the answer is always "no". It does not.

When the question is something like, "do my headphones need an amplifier?" then the answer falls under what I've written: either they do for some technical reason or they don't. Everything else is stack envy. This includes wanting -- that is, the desire rather than the requirement -- some perceived improvement in sound quality which may or may not actually exist for a given set of headphones and ears and brain and listening environment, and especially when an inexpensive widget will do just as well.

Simple as that.

I don't agree that it is that simple. What about a situation where a DAP has a well implemented true line out, yet its internal headphone amp is a substandard design with poor sonic performance? In that situation, regardless of the headphones being used, use of a well designed headphone amp through the lineout (thereby bypassing the internal headphone amp entirely) should result in improved sonic performance. That is certainly more than "stack envy," as you put it.

See the analog outputs on the right? That's all analog domain. The firmware doesn't touch any of that; all signal processing happens in the digital domain. Note carefully that there is one set of analog outputs: left channel positive/negative, right channel positive/negative, and mid rail left/right. These are split with one branch going to the line out and the other going to the headphone op-amp. You can see this for yourself in photographs of the circuit board (ask Google about "ibasso dx50 teardown").

Any firmware change that affects the headphone output will have an identical effect on the line out.

From this I can draw two possible conclusions:

First is that there are no changes from v1.2.6 to v1.2.7. Any changes that you perceive are in your own perceptions. That is, in your own mind rather than anything measurable in the real world.

Second is that there are actual, detectable changes between v1.2.6 and v1.2.7. The lack of change that you perceive between the two is in your own perceptions. That is, you want the line out to be "good" so strongly that it colors your perception of the differences.

I don't agree that it is that simple. What about a situation where a DAP has a well implemented true line out, yet its internal headphone amp is a substandard design with poor sonic performance?

"Poor" is a matter of opinion. But assuming that the amplifier suffers from a genuine design flaw as opposed to simply being relatively inexpensive then there is a clear technical fault to be rectified.

"Poor" is a matter of opinion. But assuming that the amplifier suffers from a genuine design flaw as opposed to simply being relatively inexpensive then there is a clear technical fault to be rectified.

ok. to be honest thus far i share ratinox opinion. amping is a for headset. why would a low impedance v3's (16ohm) need a amp. if you buy a decent "DAP" i assume there is a good DAC in it. but also a decent amp. otherwise i don't really think you can call it a DAP. for me DAP is a all in one. why does anyone want to stack another AMP on top of his DAP? i have read that the C5 does help against hiss. but shouldn't the low gain option on the DX50 help against hiss?

when we are talking about hard to drive headphones ok a amp is needed to fully unleash a headsets potential. But a low impedance IEM i wonder.

OFC i'm kinda newbie never owned a Amp just saying what a read around on the web. rectify and correct me educate me thats what forum is for.